Objectives and significance: The purpose of the proposed study is to observe linguistic heterogeneity (bilingualism/multilingualism, dialect variation, diglossia) in its social context in a non-western society, in order to improve cross-cultural understanding of these phenomena. South India is selected for this purpose because heterogeneity is prevalent there, and seems furthermore to be accepted much more as a routine part of life, apparently causing much less tension and conflict (except when exacerbated by politics) than is reported for many western societies. This study is expected to result in an improved cross-cultural model of language variation in social context, as well as practical lessons for problems of linguistic heterogeneity in our own society. Methodology: Several areas will be selected for study, to provide a range of variation in types of bilingualism, dialect variation, and diglossia. Materials of the following types will be collected: demographic date on incidence of bi- /multilingualism; descriptive information on local langua e variants from published and unpublished studies; detailed interview data from 25- 50 individuals in each area on the personal impact of linguistic heterogeneity (history of language acquisition, patterns of use, perception of problem, etc.); observations of language usage in a variety of social contexts; interview data (from officials, educators, etc.) on the social impact of linguistic heterogeneity; data on educational performances of bi-, mono-, and multilinguals. Sociolinguistic analysis (correlations of linguistic features with features of social context) and content analysis will be carried out in order to determine: reported and actual patterns of speech usage and their relationships to social and linguistic factors; the relationships between language competence and social background, intellectual development, and types of social interaction; the evidence for (actual and perceived) problems and advantages related to different types of linguistic heterogeneity; differences and similarities between South India and other societies studied with respect to the impact of linguistic heterogeneity on the individual and the society.